1. Field of the Invention
The present invention relates to a construction of fins of a heat exchanger for use in air conditioners such as room air conditioners, package-type air conditioners, automobile air conditioners or the like. More particularly, the invention is concerned with a construction of fins of a heat exchanger of the type having a heat transfer tube in which a heat transfer medium is circulated, with the fins being connected in a heat conducting relation to the heat transfer tube so that a heat exchange is performed between the heat transfer medium flowing in the heat transfer tube and a gas flowing through the gaps formed between adjacent fins.
2. Description of the Prior Art
In general, the heat exchanger incorporated in air conditioners has a heat transfer tube and a multiplicity of fins connected to the heat transfer tube at a substantially right angle to the latter. In order to obtain a high efficiency of heat exchange between the heat transfer medium flowing in the heat transfer tube and the air flowing through the gaps between adjacent fins in contact with the latter, each fin is provided with a plurality of louvers cut out and raised from the fin base plate. In this known fin structure, if the height of louvers is selected to be a half of the pitch of fins and the louvers are formed in rows parallel to the direction of air flow, the louvers are overlapped as viewed in the direction of air flow so that the heat transfer performance of the downstream louvers is adversely affected by the upstream louvers. Consequently, the heat transfer efficiency of the heat exchanger as a whole is lowered.
In order to overcome this problem, it has been proposed to select the height of louvers to be one third (1/3) of the pitch of fins and to form the louvers to protrude upwardly and downwardly from the fin base plate alternately, such that each fin has a portion where no protrusion is formed, a portion where an upward protrusion is formed and a portion where a downward protrusion is formed. This arrangement permits an increase of the gap between louvers in the direction of air flow. However, this arrangement inconveniently provides rows of louvers each of which is inclined at an angle .theta. to the direction of air flow. Consequently, the air flowing between adjacent louvers encounters a large flow resistance and is deflected in the direction of rows of the louvers which make the angle .theta. to the direction of incoming air. This means that the flow velocity of the air contacting the downstream louvers is decreased to lower the heat transfer efficiency on such louvers. In addition, the air flow as a whole is inconveniently deviated or offset to one side of the heat exchanger, resulting in an increased flow resistance against the air.